Writing boards (e.g., whiteboards, blackboards, etc.) are used in many different settings (e.g., academic, corporate, non-profit, residential, etc.). Text, drawings, charts, graphs, etc. may be placed on writing boards to communicate ideas during lectures, training, brainstorming sessions, etc. In order to electronically memorialize these ideas, a photograph or printout of the writing board may be taken and image processing (e.g., optical character recognition (OCR), stroke recognition, reconstruction, etc.) may be executed to extract the contents of the writing board from the image.
In an image that includes the writing board, the pen strokes on the writing board may cause variations in color due to variations in pressure while writing, the writer's technique or style, the amount of ink remaining in a marker, residues of previous images on the writing board, a worn pen tip, irregular ink distribution, etc. Similar variations in color may occur in a scanned image due to artifacts introduced during the scanning process, variable lighting on a written source as it was scanned, etc.
A user may prefer a consistent rendering of color, rather than applying subtle color variations that are likely the result of “noise factors” such as those listed above. The user's likely intent is to use a few colors, rather than many shades of the same color. It is unlikely that a user would want such inconsistencies to be maintained in an electronic document that is generated based on the image.